This invention relates to a control unit for a heating system such as a kitchen oven or a commercial microwave oven used at a fast-food store, and more particularly to such a control unit which contains a microcomputer and operates in accordance with one of many stored programs or an inputted cooking sequence.
There is shown in FIG. 1 how the control unit of a typical commercial microwave oven at a fast-food store may look. A characteristic of such a commercial microwave oven at a fast-food store is that the types of foods which can be handled are usually limited (such as hamburgers) and that they can be served fast (such as within three minutes or five minutes). Reference being made to FIG. 1, numeral 51 indicates a display window for displaying information on the cooking sequence program which is being carried out. A liquid crystal or fluorescent tube may be used for this purpose and the displayed information may include a code number 54 assigned to the particular program currently being carried out and the remaining time of heating 55a. Numerals 52 indicate dedicated keys addressed to the individual menus offered by the system. Numeral 53 indicates a start key for starting the operation of the system according to the menu addressed by one of the dedicated keys 52. Each dedicated key 52 includes a number display section 52a, a menu name display section 52b and a key pad (input key) 52c.
Such a commercial microwave oven at a fast-food store must be easy to operate. For this reason, cooking programs for items handled at the store are usually incorporated in the control unit. Another characteristic of a microwave oven at a fast-food store is to store within the system itself a few kinds of food items such that a small variety of their combinations can be made according to the customer's choice. In the case of a hamburger store, one of the choices may be between a hamburger and a cheeseburger, or relate to the size such as "standard", "jumbo" and "mini". A commercial microwave oven at a fast-food store usually incorporates five to ten different programs. In most cases, a key is dedicated to each program as shown in FIG. 1 such that the user needs only to select a program and press the corresponding key once. In fast-food stores where each second counts, it is essential that the microwave oven be operable with one touch of a key. For this reason, it has been a common practice to store various cooking programs in a ROM means which has been made an inseparable part of the control unit.
Although the number of choices is limited in most such applications, there can be popular (frequently used) choices as well as unpopular (not so frequently used) choices. If the store wants to replace an unpopular menu with a new menu developed at the store itself, however, the existing program already incorporated in the system cannot be utilized. From the point of view of the oven maker, on the other hand, it is not economically beneficial to receive many small orders from different types of businesses. In short, the consumers nowadays welcome the quick services of fast-food stores but at the same time want varieties and options, and the fast-food stores must keep creating new menus in order to survive in this world. In other words, there is a need for commercial microwave ovens of a new type which can be profitably used by fast-food stores with such requirements as described above.
With the recent progress in integrated circuits (IC) technologies, the memory capacities of individual IC memories have increased and the number of cooking sequence programs which can be stored in the electronic control unit of an ordinary microwave oven has also increased. The user nowadays can select a program from a large number of available menus. The control unit of such a microwave oven usually operates in the following two-step sequence. In the first step, the user selects a menu. In the second step, a cooking sequence program corresponding to the selected menu is retrieved. The first step is for the user to decide. With respect to the second step, a commonly adopted method has been to assign program codes to the individual cooking sequence programs of each menu such that the user operates the number keys on a panel to input a code number to access the desired cooking sequence program. Although it was usually the housewife's job to select the daily menus for the family, an increased number of women go out to work nowadays and such working wives do not have much time to plan a nutritiously balanced menu on an everyday basis. Some menus are very often repeated at frequent intervals but it is not easy for the planner of a meal to remember when it was the last time the same plate was prepared before. For this reason, the tendency is to repeat whichever menus that are familiar to him or her in spite of the large variety of cooking sequence programs available with the system. In other words, a large fraction of the many programs edited by the oven maker tends to remain unused. Although the number of programs that can be offered with an oven may further increase in the future, the number of access keys dedicated to the individual programs is limited by the physical size of the control unit. This means that the user would still have to memorize the program codes or to keep consulting the menu book listing the codes.